| NEW
MATERIALS FOR MOBILE BEARING KNEE PROSTHESIS - |
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TITANIUM NITRIDE COUNTERFACE COATINGS FOR REDUCTION IN
POLYETHYLENE WEAR |
V.C.
JONES, D.D. AUGER, M.H. STONE, J. FISHER
ABSTRACT
The main
aim of this study was to investigate the application of Titanium
Nitride (TiN) coating to femoral and tibial counterfaces for
the reduction of polyethylene wear under standard conditions
and conditions that simulate the presence of third body counterface
damage.
The wear
of polyethylene and the potential for wear debris induces
osteolysis remains a long term potential concern for the survivorship
of articial knee joints. A low contact stress multidirectional
wear model of mobile bearing knees has been developed. The
model which applies a load of 180 N is effectively a one fifth
scale model of the mobile bearing knee. The wear rates in
this model can be multiplied by a factor of five to achieve
an approximate prediction of wear in total knee replacement.
The surface
roughness of the coating is important, as the increase in
roughness after coating can lead to an increase in polyethylene
wear. The benefit of the coating is shown in its resistence
to scratching. Under these conditions of simulated third body
scratching the wear rate of the polyethylene in the TiN coated
surfaces with smaller scratch lips was significantly less
thatn on the scratched, uncoated Cobalt Chrome counteface.
Ceramic
like coatings have the potential to reduce long term wear
in knee prosthesis.
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